The car was overheating slightly due to insufficient level of coolant last 3 days.
After topping up the radiator with water, I bled the system using the screw on the radiator.
However, the air bubbles kept appearing even after, say, 2 minutes, and it seemed the water turned brownish during the process.
It also seems that the valve in heater matrix is shot, the heating behaves erratically (no heat when turned on, then it heats slightly when turned off etc., linkage was checked and adjusted twice to no avail).
I checked the engine oil and there were no signs of water/oil emulsion on the dipstick.
Can the air appearing in the water be considered a symptom sufficient for a blown gasket diagnosis, or am I worrying uselessly?
Thanx.

When you turn off the ignition does the water still expand? if it does then you have an air bubble somewhere. My technique is to pump the water by squeezing the big pipes from the radiator.

Having a blocked or otherwise not working heater can cause issues like this. My uno had this problem, I repaired the heater (replaced the matrix) and the problems when away.

Another thought, if you are having issues with your heater you could try bypassing it and see if your problems go away. Its really easy on the FIRE, you just remove that plastic junction thing and replace it with a piece of pipe (Me and Alex used a 12mm deep socket once )

(CZ)enda,
My first thought is that with the heater valve not working properly, there may be air trapped in the heater - and it sounds as though rusty water is also still in the heater. I remember filling my Uno Turbo when it had a blocked heater, and it was near-impossible to get the air locks out of the cooling system.

So I think you should get a large tub and place it under the heater valve, take it off, and see if you can get it moving again. I boiled mine up in a saucepan of water on the stove (tasty!)...

Then I sprayed it with silicone spray and it started working again. It's not perfect to this day, but thanks to jjhepburn I have a spare waiting to go on.

Anyway, once you have the heater clear and working to full output, I think you will have more success filling and bleeding the system (and we can worry about the head gasket later )

Some specialists have a special piece of kit that looks like a battery tester. A small amount of special blue fluid is put in the glass tube, then the rubber bulb is squeezed and released to draw vapours from the coolant expansion tank (radiator). If the blue fluid turns green, combustion gases may be present indicating a (however slight) head gasket failure.

A more major head gasket failure will show as creamy oil buildup on the radiator cap, white mayonnaise in the oil cap or on the dipstick, steam from the exhaust (on a dry day with engine hot, in cold weather it's much too close to call with the normal condensation) and of course, a dropping coolant level (more than 0.5L/month) with no obvious leaks.

Cheers,
-Alex

When you change coolant, you should set the heater to fully open, open the bleed screw at the intake besides the bulk head. Start the engine with the filler cap off. When water comes out the bleed valve, close it. Let the engine idle for 10 minutes until the fan cuts in (with the heater at full). The thermostat will open slightly before the fan or at the same time, letting coolant into the engine and system, and the coolant level will drop. Shut off engine and refill with coolant until max. This might cure it.

Well, just to report the progress...
The case is closed, the water was leaking from the point where the lower hose attaches to the radiator, possibly the radiator itself. I had to cannibalize the relics of my first 45 and replaced the radiator, heater matrix and the heater valve.
Conclusion:
a) Do not believe the part of the Haynes where is says the heater matrix can be removed in situ. The tape that holds it in place is extra-sticky and I had to remove and disassemble the whole heating/venting assembly.
b) Modernization can make things worse. The old heater valve with "rotate to open" slide seems to be better design than the newer "push to open" slide. Retrofitting the older valve made the heating little-finger-smooth to operate.

Head gasket change forgotten

(CZ)enda said:

b) Modernization can make things worse. The old heater valve with "rotate to open" slide seems to be better design than the newer "push to open" slide. Retrofitting the older valve made the heating little-finger-smooth to operate.

Click to expand...

This is very interesting... I bought a brand-new heater valve in a FIAT bag a couple of years ago, and it was the rotating type. The one that came out of my car (and looked original) was the sliding type. I thought the rotating type was better, as well.

So, if you retro-fitted the older (rotating) type, did you have to clean it out/unseize it? How did you do it?

The control doesn't seem to be very linear with either design - tends to be all or nothing Quite a number of other cars - both newer and older - close off the airflow through the matrix rather than trying to turn the water on and off.

Glad you've got the system working again.

Thanks,
-Alex

Well, the rotating valve did not need any unseizing for smooth operation. It came from 1987 45. I always used antifreeze in this car, blueish G48 for aluminium blocks, for maybe 5 - 6 years. Surprisingly, this kind of antifreeze indeed has the rust protection qualities as stated on the package, because there were absoulutely no signs of rusty sludge when I was flushing the 1987 radiator, matrix and the valve itself.
On the other hand, the cooling system of the 1989 45 I wanted to fix was full of rust. I bought the car about a year ago and used the same antifreeze, but I did not flush the system properly, only drained ordinary water it was filled with and refilled with new antifreeze.
This was probably a mistake.
I tried to set the 1989 valve moving by flushing it, then applied penetrating oil, then lithium grease onto the slide. None of these actions brought any results and, surprisingly, the penetrating oil made the action of the rectangular slide even worse.
I noticed there are two tiny holes in the rectangular slide, probably to provide for certain minimum flow when the valve is closed, which (my speculation) is used to protect the matrix from clogging.
The rotary valve seems to provide for this minimum flow by very narrow gap between the slide and the inner side of the valve housing (even when in fully closed position, it still allows for some flow - I tried this with a gardening hose attached.).

My theory for unsatisfactory smoothness of the newer valve is
a) there may be a flake of rust caught between the slide and inner area of the housing, caught in such place that it cannot be flushed
b) it was not a good designing idea to put the gear transferring the action of the string that operates the slide into the housing. This is how it is on the newer one, while the 1987 one has the mechanism outside the housing, where the lever it is not exposed to rust particles that may be present in the cooling water. Plus, I think that leverage is used more effectively on the earlier design.

If you were able to get the older type with rotary action... Is it possible that the rectangular slide in/out valve was only temporary design solution, replaced with the original one after it has proven less satisfactory?
It would be interesting to find out which of these valves was used on, say, 1993 Uno.

Ditto for my experience - exactly the same, with the sliding type seizing even more with the silicone spray I tried to use. I think it's the choice of material used. And I noticed those small holes too. Didn't work in my case - it was all blocked solid when I bought the car. Must have been miserable for the previous owner, driving the car in the wintertime with no heater.

I suggest that your 1987 Uno may have had the valve replaced before you bought it?

-Alex

alexGS said:

I suggest that your 1987 Uno may have had the valve replaced before you bought it?

Click to expand...

I do not think so, I seem to remember there was "6" (i.e. 1986) on the dial-like stamp present on the plastic pieces... but I am not going to remove the valve again just to double-check